1. Field of the Invention
The present invention relates to a semiconductor device used for a liquid crystal display (LCD) device and, more particularly, to a flexible film package.
2. Description of the Related Art
In recent years, the rapid development of LCD-related technologies has accelerated the shift to an information-oriented society. In general, data communication electronic devices in which an LCD is utilized are required to be thin, light-weight, and compact for portable use. Thus, new methods of mounting semiconductor chips on semiconductor packages have been proposed for LCD devices.
While micro ball grid array (μ-BGA)-type semiconductor packages were widely used for conventional data communication electronic devices that incorporated an LCD, flexible film packages are currently being increasingly utilized. A flexible film package is a semiconductor package in which a semiconductor chip is directly attached onto a flexible thin-tape-type film so as to reduce the area occupied by the mounted semiconductor chip.
Flexible film packages do not generally utilize solder balls as external connection terminals but instead rely on an anisotropic conductive film (ACF) that is directly attached to a printed circuit board (PCB) or a glass panel for an LCD. The flexible film packages include broad categories such as tape carrier packages (TCP), chip on film (CoF) packages and other configurations known in the packaging arts.
FIG. 1 is a plan view of a conventional flexible film package module, illustrating the manner in which the flexible film package module is mounted on an LCD substrate. As illustrated in FIG. 1, in a conventional LCD device, semiconductor packages for controlling light, for example, a plurality of flexible film packages 100, are mounted on a top surface of a glass panel 300, and semiconductor packages 600, on each of which a gate integrated circuit (IC) for controlling voltage may be mounted, are formed on a lateral surface of the glass panel 300.
The flexible film packages 100 are bent and mounted on the glass panel 300 and connected to a PCB 200, which is positioned behind the glass panel 300. The PCB 200 may be considerably larger than the individual packages so that a plurality of flexible film packages 100 may all be attached thereto. A plurality of semiconductor devices 210 for operating the LCD device may be installed at other locations on the PCB 200.
FIG. 2 is a plan view of one flexible film package 100 shown in FIG. 1. As illustrated in FIG. 2, no semiconductor chip has yet been mounted on the flexible film package 100. The flexible film package 100 is formed from a polyimide film 10, which has an excellent coefficient of thermal expansion (CTE) and is highly durable. A chip paddle 18 is formed on the polyimide film 10, and the circuit pattern of the chip paddle 18 is, in turn, connected to a copper pattern 16 that is configured for extending and attaching to both the PCB and the glass panel.
A semiconductor chip (110 of FIG. 3) may be attached to the chip paddle 18 using bump connectors and one or more slit holes 20 may be formed in the polyimide film 10 so that the polyimide film may be more easily bent. In FIG. 2, B1 designates a portion of the flexible film package 100 that is attached to the PCB while B2 designates a portion of the flexible film package 100 which is attached to the glass panel. TP1 and TP2 designate conductive pads that may be used for electrical inspection and testing conducted after the flexible film package 100 has been completed. A1 designates a region where a solder resist may be is coated in order to protect the copper pattern 16 from damage or corrosion resulting from to external forces or contaminants and shorts between leads caused by conductive particulates or other foreign materials. A2 designates a cutting line along which each of the individual flexible film packages 100 may be separated from other adjacent flexible packages and excess polyimide film after the assembly and electrical inspection have been completed to obtain an individual flexible film package.
FIG. 3 is a cross-sectional view of the flexible film package module of FIG. 1, illustrating the shape in which the flexible film package module is bent. As illustrated in FIG. 3, the bent flexible film package 100 is attached to edges of a glass panel 300 and a PCB 200. A protective cover 700, typically metal, may be disposed outside the glass panel 300 and the PCB 200. A light emission unit 400, for example, a fluorescent light, may be mounted between the glass panel 300 and the PCB 200, with a filler 500, through which light may be transmitted, filling the space between the glass panel and the PCB. Thus, light from the light emission unit 400 transmits the filler 500 and penetrates the glass panel to create an image.
As illustrated in FIG. 3, the copper pattern 16 formed on the polyimide tape may be connected to the glass panel 300 and the PCB 200 using an ACF 180. Reference numeral 202 denotes a copper pattern formed on the PCB 200.
A conventional flexible film package is disclosed in U.S. Pat. No. 6,061,246, dated May 9, 2000, entitled “Microelectric Package Including Flexible Layers and Flexible Extensions, and Liquid Crystal Display Modules Using the Same.” However, conventional flexible film packages have certain limitations. For example, although the polyimide films used to form the flexible film package tend to have excellent durability and CTE, they also tend to be very expensive so that a semiconductor package manufacturing process that uses a polyimide film will tend to be more costly than one that does not. Substantially, when a conventional flexible film package is manufactured, the production cost ratio between the semiconductor package and the incorporated semiconductor chip can be as much as 6:1, a cost ratio that is generally higher than that of other kinds of semiconductor packages. Therefore, reducing the production cost for flexible film semiconductor packages would strengthen the price competitiveness of such packages.